Featfz j



(No Model.)

F. J. WEIS$.

AIR PUMP.

Patented Mar. 31, 1885.

Jiwfidor 16am cI Mzlsa 010 L mn' u her. Washington. D. c.

,, section of the cylinder, piston, and slide-valve,

UNITED STATES PATENT OFFICE.

FRANZ J. WVEISS, OF BASLE, SVVITZER LAND.

AIR-PUMP.

F5PECIFICATION forming part of Letters Patent No. 314,766, dated March 31, 1885.

Application filed December 27, 18:52. (No model.) Patented in England July 26, 1882, No. 3,551; in Germany November 21, 1882, No. 22,775; in France November 25, 1882, No. 150,319; in Belgium December 15, 183-2, No. 43,398, and in Italy March 31, I883, XVI,

To all whom it may concern:

Be it known that I, FRANZ JOSEPH Wnrss, a citizen of the Republic of Switzerland, re siding in the city and canton of Basle and Re public of Switzerland, have invented certain new and useful Improvements in Air-Pumps, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to improvements in air-pumps, and has for its object to reduce the detrimental effect of the clearance'space, or space between one end of the cylinder and the piston, when the latter is at that end of its stroke. In other words, the object is to conduct the compressed air from the clearancespace to the suction side of the piston.

The invention consists in the construction and arrangement of parts,which will be hereinafter more fully describcd,and then set forth in the claim.

In the drawings, Figure 1 is a longitudinal the figure also representing the position of the piston during its real working period, and showing a slide-valve which has ports for the outlet of the compressed air, and'also carries a back-pressure valve. Fig. 2 is a view of the parts shown in Fig. 1 when the piston has completed its stroke and the channel in the slide-valve is in communication with the clearance-space at one end of the cylinder for conducting the compressed air in said space to the suction side of the piston.

The letter A in the figures designates the cylinder of an aircompressing or vacuum pump, and B is the piston, which operates therein in the customary manner. The air to be compressed or exhausted is admitted into a chamber or space, 0, which is open to the external airor chamber to be exhausted. Over this air-inlet chamber is arranged a slideon the working-cylinder. At one side of the valve chamber or chest is located an eductionchamber, E, for the compressed or exhausted air, and a valve, R, carried by the slide-valve D and arranged in said chamber. serves to close the cominn nication with said valve-chamber after the piston has completed its stroke and forced the airfrom the working-cylinder into the eduction-chamber. I11 other words, this valve is opened in an outward direction by the air passing from the cylinder, and is closed and held to its seat by the back-pressure of the air in the chamber E. The eccentric or cam for imparting motion to the slidevalve D follows the crank of the engine-shaft at an angle of about ninety degrees, and a pitman serves to connect it with the valve in such a manner that in the operation of said valve the connection of the channel and ports 61 with the space in front of the piston with that behind the same is effected at the medium position of the valve, as in Fig. 2. The outer and inner laps of the slide-valve are of such size that the channel a is about to be closed when the outer and inner edges of the slide-valve in their turn open the air-channels for the purpose of connecting the pressurespace with one end of the cylinder and the suction-space with the other end thereof. Moreover,if the outer and inner laps are equal and the cam or eccentric is arranged at suchan angle that the outer or in turn the inner edges of the slidevalve shut off the air channels or passages exactly'at the end of a stroke of the piston, then the required conditions are attained-that is to say, an effective delivery of air is caused until the piston has completed its stroke, and a connection of the spaces on each side of the piston is effected immediately after the completion of the stroke and while the pressure and suction spaces are shut off.

The valve R is employed for the purpose of enabling the piston to operate without encountering any back-pressure of the air in the eduction-chamber, and for this reason it can opcrate with greater freedom and with less resistance than if said valve were absent. The valve D is made sufficiently long to extend beyond the channels F, leading to the cylinder, and it has outlet-ports i and carries the backpressure valve R, that fits over said outletloo ports i. The valve R is fitted on a suitable guide-stem, S, projecting from the rear or outer face of the valve D, and a spring, T, together with the pressure of the air in the eductionchamber, serve to hold it closed until such time as either of the ports 73 is brought opposite the passage in the cylinder through which the compressed air is being expelled by the action of the piston. In other words, when the piston is expelling the air from the working-cylinder the valve R is opened to allow the air to enter the eduction-chamber. Aircompressing or vacuum pumps constructed as above described work noiselessly and produce better effects with the same dimensions than pumps heretofore devised, such results being due to the fact that the compressed air in the clearance-space ofthe cylinder is at the proper time conducted into the suction-space of the cylinder,that the piston will immediately commence to suck in air when it is making its return stroke. The slide-valve also works with out noise and friction.

I am aware that a Valve mechanism for triphammers has heretofore been proposed in which a slide-valve is provided with ports that serve to establish a communication between the top and bottom of the piston and working-cylinder in order to allow a portion, of thesteam or other fluid which has raised the hammer to pass from the lower to the upper side of the piston, thereby equalizing the pressure on both sides of the piston, and allowing the hammer to descend with a velocity due to gravitation alone. Such construction,

therefore,I disclaim, as it forms no part of my In an air-compressing or exhaust pump,tl1e

combination, with the working-cylinder, the piston, and the valve-chest having ports leading to the ends of the cylinder, and provided with an air-inlet cha1nber,ofaslide-valve hav ing a longitudinal channel and end ports communicating therewith, outletports. for the 1 compressed air and carrying a back-pressure:

valve, and an eduction-chanlber in which said slide-valve is located, all constructed and rela'-' tively arranged substantially as described.

In testimony whereof I have signed my name to this specification in the-presenceof twosnbscribing witnesses.

FRANZ JOSEPH WEISS;- Witnesses: I

HENRY HOFAOKER,

AUGUST WINOKHARDT. 

